1. Field of the Invention
This invention relates to a process for use in the purification of nitrocellulose, and more particularly to a treatment of the fibrous nitrocellulose product which treatment facilitates removal of traces of sulfuric acid.
2. BRIEF DESCRIPTION OF THE PRIOR ART
Nitrocellulose is presently made by reacting a cellulose feed stock such as cotton linters or wood pulp, with a mixture of nitric and sulfuric acids. The nitric acid reacts with the cellulose, causing nitrate radicals to replace hydroxyl radicals and forming water as a reaction product. This is a reversible reaction, thus: EQU R--OH+HNO.sub.3 .revreaction.R--NO.sub.3 +H.sub.2 O
Normally, the reaction would not proceed far enough to yield a highly nitrated product, but the sulfuric acid introduced with the nitric acid takes up the water formed and permits the reaction to proceed to the desired degree. After the nitration has been performed, it is necessary to purify the nitrocellulose by removing the sulfuric acid entrapped in the fibrous product. If it is not removed, the nitrocellulose will not be stable, but rather will break down with the evolution of heat and fumes ultimately resulting in explosion, fire, or at least severe deterioration of the nitrocellulose. Thus, manufacture of nitrocellulose based materials such as propellants and explosives with long shelf lives is highly dependent on purification and stabilization with thorough removal of sulfuric acid traces.
The purification system commonly used today is a batch operation involving lengthy boiling and poaching operations. The process requires the consumption of large quantities of heat energy, steam and water and the equipment used in carrying out the process requires housing in a large and costly plant facility.